﻿260 Dr. J. W. Low on the Velocity of Sound in 



The values of 7, the constant for friction and conduction of 

 heat, are as follows: — 



Tube. 



c r 



e r 



9,- 



c n . 



c lir 



I 



0-005C99 



0-004490 



0-004424 



0004284 



0004078 



II 



4718 



4307 



4137 



4457 



4706 



Ill 



4592 



4615 



4575 



4873 



5240 



Mean =0 004577. 



The ratio of the specific heats, calculated in the same way 

 as for air, I found to be 1*2883. Rontgen* gives 1*3052 and 

 Miillerf 1*2653. 



To recapitulate, — 



1. KirchhofPs formula for the determination of the velocity 

 of sound in tubes holds good for carbonic acid as well as for 

 air if the velocity in the free gas = 257*03 metrej, and the 

 constant for friction and conduction of heat =0*004577. 



(2) The ratio of the specific heats for carbonic acid is 

 1*2883}. 



§ 5. Hydrogen. 



The remodelling of the apparatus for gases lighter than air 

 caused much trouble. In its final form I simply inverted the 

 whole apparatus as employed for carbonic acid. It was 

 now in fact a siphon ; the open eud of the tube was below 

 and the stopcock above. The few drops of water that trickled 

 out I led aside with a tail of lamp-wick. The method of 

 filling was the same as for carbonic acid, only here every- 

 thing was inverted. 



On account of the extraordinary tenuity of this gas, the 

 wave-lengths are very great, and much longer tubes than 

 before were necessary. I soon found that the energy of the 

 vibrating mass of the gas was too small to set the membrane 

 of the tympanum properly in vibration, and that exact readings 

 of the maxima were unattainable. 



The following readings were taken with tube II. and fork c„ 

 at a temperature of 15° C. : — 



* Pogg. Ann. cxlviii. p. 812 (1874). 

 t Wied. Ann. xviii. p. 116 (1883). 

 X Corrected on page 264. 



